1. Field of the Invention
The present invention relates to a projection type color liquid crystal display (LCD) apparatus used in a personal computer, a television set or a video tape recorder.
2. Description of the Related Art
A first prior art projection type color LCD apparatus includes three dichroic mirrors for selectively reflecting blue, red and green components of a luminous flux, and three LCD elements each receiving the blue, red and green components, respectively, of the luminous flux. Thus, three color images obtained by the three LCD elements are combined to obtain a color image on a screen.
In the first prior art projection type color LCD apparatus, however, since use is made of three LCD elements, the apparatus becomes expensive and large in size.
A second prior art color LCD apparatus includes a single LCD element associated with color filters such as blue, red and green filters. Since use is made of one LCD element, the apparatus becomes inexpensive and small in size.
In the second prior art projection type color LCD apparatus, however, the optical utilization efficiency of the available light is low. That is, the blue filter passes the blue component therethrough, but the blue filter absorbs the red and green components. Also, the red filter passes the red component therethrough, but the red filter absorbs the blue and green components. Further, the green filter passes the green component therethrough, but the green filter absorbs the blue and red components. Thus, only one-third of the available light is utilized.
A third prior art projection type color LCD apparatus includes a color separation section formed by dichroic mirrors which receive a luminous flux to selectively reflect a plurality of color components of the luminous flux individually at different angles. Convex lenses of a microlens array converge the reflected color components into different pixels of an LCD element (see JP-A-4-60538). This will be explained later in detail.
Thus, in the third prior art projection type color LCD apparatus, since portions of blue, red and green luminous fluxes are selectively incident to the pixels of the LCD element, color filters are unnecessary, so that the optical utilization efficiency of the available light can be increased without the loss of light due to the color filters.
In the third prior art projection type color LCD apparatus, however, natural light is incident to a polarization plate as a polarizer, and one of the P-polarized component and the S-polarized component of the natural light is absorbed in the polarization plate, so that the optical utilization efficiency of the available light is still low. In addition, since the polarization plate is heated by the absorption of one of the P-polarized component and S-polarized component, the polarization plate is deteriorated. Further, it is difficult to adjust the angles of the dichroic mirrors, and also, the adjusted angles of the dichroic mirrors are easily deviated from each other by vibration of the apparatus.